(1) Field of the Invention
The present invention relates to a refrigeration system and a method of operation therefor, and more particularly, to a refrigeration system for use in an automotive air conditioner which uses a gas harmful to the human body as a refrigerant and a method of operation for such a refrigeration system.
(2) Description of the Related Art
A refrigeration system used in an automotive air conditioner generally comprises a compressor for compressing a refrigerant circulating through the refrigeration cycle, a condenser for condensing the compressed refrigerant, a receiver for temporarily storing the refrigerant circulating through the refrigeration cycle while at the same time separating the condensed refrigerant into gas and liquid, an expansion valve for adiabatically expanding the liquid refrigerant, and an evaporator for evaporating the expanded refrigerant and then returning the refrigerant to the compressor (see Japanese Unexamined Patent Publication No. 2002-147898 (Paragraph No. [0001], FIG. 1), for example).
In the refrigeration cycles of automotive air conditioners, chlorofluorocarbon substitute gas has hitherto been used as the refrigerant, but in consideration of global warming, there has been a demand for refrigerants with smaller Global Warming Potential. For example, carbon dioxide, propane, etc. have been proposed as such refrigerants.
In the case of using carbon dioxide, propane, etc. as the refrigerant, however, a problem arises in that, if the refrigerant leaks because of damage to the evaporator arranged in the vehicle compartment or to piping installed in the vehicle compartment, the occupants can possibly be put in a grave situation such as suffocation due to deficiency of oxygen or outbreak of fire.